Epidemiological parameters of coronavirus disease 2019: a pooled analysis of publicly reported individual data of 1155 cases from seven countries

Shujuan Ma; Jiayue Zhang; Minyan Zeng; Qingping Yun; Wei Guo; Yixiang Zheng; Shi Zhao; Maggie H Wang; Zuyao Yang

Incubation period and serial interval are also key parameters for epidemiological modelling in predicting the transmission dynamics, including the basic reproduction number (R0). R0 is defined as the average number of secondary cases caused by a single infectious individual in a totally susceptible population. 18 Estimation of R0 may require the knowledge of latent period and infectious period, 19, 20 which are both difficult to measure directly. For a disease that is not infectious until onset of symptoms, latent period is equivalent to incubation period, and infectious period can commonly be approximated by the difference of serial interval minus incubation period. 18 However, for COVID-19, the latent period appears to be shorter than incubation period as pre-symptomatic transmission might occur, 16, 17 and this should be accounted for when estimating R0. To our best knowledge, no published studies estimated the latent period of COVID-19, or how often and approximately at which time point the disease could be transmitted prior to the symptomatic onset.